Preoperative parenteral nutritional support may produce a small absolute reduction in post-operative morbidity, but its cost becomes prohibitive.

Preoperative enteral nutritional support, especially if carried out in the home, may be of benefit (using the most optimistic interpretation of a small number of trials) ; if so, it is an economically defensible intervention.

Particular nutrients or diets may have specific effects on certain disease processes.

Indirect comparisons have suggested that elemental diets can be used to treat flares of Crohn's disease (perhaps because putative food antigens are removed).

However, corticosteroid therapy is more efficacious.

Furthermore, it is less expensive to employ 6-mercaptopurine as the next modality in steroid failures.

Branched-chain amino acid infusions may have some effect on hepatic encephalopathy, but again, lactulose is less expensive. (...)